JP2009227575A - Method for producing synthetic silica powder - Google Patents
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本発明は、四塩化珪素の加水分解によって合成シリカ粉を生成する方法において、生産性がよく合成シリカ粉を製造する方法に関する。 The present invention relates to a method for producing synthetic silica powder with good productivity in a method for producing synthetic silica powder by hydrolysis of silicon tetrachloride.
合成シリカ粉の湿式製法として、アルコキシシランを原料とする方法が知られている。例えば、特開昭６２−１７６９２８号公報（特許文献１）には、アルコキシシランを酸またはアルカリの存在下に加水分解してシリカ質のゲルを生成させ、これを脱水乾燥した後に焼成してシリカガラス粉を製造する方法が記載されている。また、特開平６−３２９４０６号公報（特許文献２）には、アルコキシシランにシリカ微粉末を加えて加水分解することによって、焼成時のシラノール残留量を低減する方法が記載されており、特開平６−３４０４１１号公報（特許文献３）には、ゲルの乾燥手段として水酸化ナトリウムなどのアルカリ水溶液で内壁を洗浄した乾燥機を用いることによって、焼成時の未燃カーボン等の発生を防止する方法が記載されている。 As a method for producing synthetic silica powder, a method using alkoxysilane as a raw material is known. For example, in JP-A-62-176928 (Patent Document 1), an alkoxysilane is hydrolyzed in the presence of an acid or an alkali to form a siliceous gel, which is dehydrated and dried and then calcined. A method for producing glass powder is described. Japanese Patent Application Laid-Open No. 6-329406 (Patent Document 2) describes a method of reducing silanol residue during firing by adding silica fine powder to alkoxysilane and hydrolyzing it. Japanese Patent No. 6-340411 (Patent Document 3) discloses a method for preventing generation of unburned carbon and the like during firing by using a dryer whose inner wall is washed with an alkaline aqueous solution such as sodium hydroxide as a gel drying means Is described.
四塩化珪素の加水分解によって合成シリカ粉を製造する方法も知られており、例えば、特開昭６２−２１７０８号公報（特許文献４）には、純水を攪拌しながら四塩化珪素を加えて加水分解させ、生成したシリカ質のゲルを加熱して残留塩素を揮発除去した後に、乾燥し粉砕後、焼成してシリカ粉を製造する方法が記載されている。また、特開昭６２−３０６１３号公報（特許文献５）には、純水に代えて塩酸水溶液を用い、容器内の塩酸水溶液を攪拌しながら四塩化珪素を添加してシリカ質のスラリーを生成させ、該スラリーを脱水乾燥してシリカ粉を回収する方法が記載されている。 A method for producing synthetic silica powder by hydrolysis of silicon tetrachloride is also known. For example, in Japanese Patent Application Laid-Open No. 62-21708 (Patent Document 4), silicon tetrachloride is added while stirring pure water. It describes a method for producing silica powder by hydrolyzing and heating the produced siliceous gel to volatilize and remove residual chlorine, followed by drying, grinding, and firing. Japanese Patent Laid-Open No. 62-30613 (Patent Document 5) uses a hydrochloric acid aqueous solution instead of pure water, and adds silicon tetrachloride while stirring the hydrochloric acid aqueous solution in a container to produce a siliceous slurry. And a method of recovering silica powder by dehydrating and drying the slurry.
従来の合成シリカ粉の製造方法において、アルコキシシランを用いる方法はコスト高であり、また原料に起因するシラノールが残留する懸念がある。四塩化珪素の加水分解を利用する方法は、シラノールを含まないので高純度のシリカ粉を製造できる利点がある。 In the conventional method for producing synthetic silica powder, the method using alkoxysilane is expensive, and there is a concern that silanol resulting from the raw material remains. The method using the hydrolysis of silicon tetrachloride is advantageous in that it can produce high-purity silica powder because it does not contain silanol.
一方、四塩化珪素の加水分解を利用する方法は、以下の式[１]に従って反応が進むが、副生した塩酸が水に溶解して液中の酸性度が高くなるとゲル化し易くなり、水１０００ｇに対して、四塩化珪素に約１７０ｇを投入した段階で溶液全体がゲル化し、これより多くの四塩化珪素を加水分解することができない。従って、水１０００ｇあたり、シリカ(ＳｉＯ2)約６０ｇしか生成せず、製品(ＳｉＯ2粉)の収率は５〜６％程度にとどまる。このため四塩化珪素の加水分解によってシリカ粉を製造する方法では、ゲル中のシリカ含有量を高めることが重要な課題である。 On the other hand, in the method using the hydrolysis of silicon tetrachloride, the reaction proceeds according to the following formula [1]. However, when the by-product hydrochloric acid dissolves in water and the acidity in the liquid increases, gelation easily occurs. When about 170 g is added to 1000 g of silicon tetrachloride, the entire solution gels, and more silicon tetrachloride cannot be hydrolyzed. Accordingly, only about 60 g of silica (SiO 2 ) is produced per 1000 g of water, and the yield of the product (SiO 2 powder) is only about 5 to 6%. For this reason, in the method for producing silica powder by hydrolysis of silicon tetrachloride, it is an important issue to increase the silica content in the gel.
ＳｉＣｌ4 （liquid）＋５６Ｈ2Ｏ（liquid） →
Ｓｉ(ＯＨ)4 （solid）＋ ４ＨＣｌ（liquid） ＋５２Ｈ2Ｏ（liquid） …… [１]
SiCl 4 (liquid) + 56H 2 O (liquid) →
Si (OH) 4 (solid) + 4HCl (liquid) + 52H 2 O (liquid) ...... [1]
Ｓｉ(ＯＨ)4 （gel）＋ ４ＨＣｌ（liquid） ＋５２Ｈ2Ｏ（liquid）→
ＳｉＯ2 （solid）＋ ４ＨＣｌ（gas） ＋５６Ｈ2Ｏ（gas） …… [２]
Si (OH) 4 (gel) + 4HCl (liquid) + 52H 2 O (liquid) →
SiO 2 (solid) + 4HCl (gas) + 56H 2 O (gas) ...... [2]
上記式[１]のＳｉ(ＯＨ)4 （solid）が、架橋を形成して、Ｓｉ(ＯＨ)4 （gel）ゲルが生成する。上記式[２]に示すように、このゲルが加水分解してシリカとなり、これを乾燥してシリカ粉を得る。 The Si (OH) 4 (solid) of the above formula [1] forms a crosslink and a Si (OH) 4 (gel) gel is generated. As shown in the above formula [2], this gel is hydrolyzed to become silica, which is dried to obtain silica powder.
このため、上記四塩化珪素の加水分解において、ゲル中のシリカ含有量が非常に低く、塩酸と水の量が多いために、塩酸と水を蒸発させるエネルギーが多く必要となり、結果、製品コストが非常に高いと云う問題がある。 For this reason, in the hydrolysis of silicon tetrachloride, since the silica content in the gel is very low and the amount of hydrochloric acid and water is large, a large amount of energy for evaporating hydrochloric acid and water is required. There is a problem that it is very expensive.
本発明は、四塩化珪素の加水分解を利用した合成シリカ粉の製造方法において、従来の上記問題を解決したものであり、四塩化珪素の加水分解によって副生する塩酸を中和しながら反応を進めることによってゲル化を遅らせ、四塩化珪素の加水分解量を多くして生産性を高めた合成シリカ粉の製造方法を提供する。 The present invention solves the above-mentioned conventional problems in a method for producing synthetic silica powder utilizing hydrolysis of silicon tetrachloride, and reacts while neutralizing hydrochloric acid by-produced by hydrolysis of silicon tetrachloride. Provided is a method for producing a synthetic silica powder that is delayed in gelation and increased in productivity by increasing the amount of hydrolysis of silicon tetrachloride.
本発明は、以下に示す構成によって上記課題を解決した、合成シリカ粉の製造方法に関する。
〔１〕四塩化珪素の加水分解によってシリカ粉を製造する方法において、加水分解で副生する塩酸に水酸化アンモニウムを添加して中和しながら反応を進行させてシリカ質のゲルを生成させ、該ゲルを乾燥してシリカ粉にすることを特徴とする合成シリカ粉の製造方法。
〔２〕容器内の純水を攪拌しながら四塩化珪素と水酸化アンモニウムを添加し、溶液のｐＨを酸性域に制御してシリカ質のゲルを生成させる上記〔１〕に記載する合成シリカ粉の製造方法。
〔３〕容器内の純水を攪拌しながら四塩化珪素を添加すると共に水酸化アンモニウムを少量づつ添加してｐＨ１〜２でシリカ質のゲルを生成させる上記〔１〕または上記〔２〕に記載する合成シリカ粉の製造方法。
〔４〕回収したゲルを２００℃〜３００℃で乾燥した後に、粉砕分級して粒度調整し、さらに１００℃〜１５００℃で高温処理して合成シリカ粉を回収する上記〔１〕〜上記〔３〕の何れかに記載する合成シリカ粉の製造方法。
The present invention relates to a method for producing synthetic silica powder, which solves the above-described problems with the following configuration.
[1] In a method for producing silica powder by hydrolysis of silicon tetrachloride, a reaction is allowed to proceed while neutralizing by adding ammonium hydroxide to hydrochloric acid by-produced by hydrolysis to produce a siliceous gel, A method for producing synthetic silica powder, wherein the gel is dried to form silica powder.
[2] Synthetic silica powder as described in [1] above, wherein silicon tetrachloride and ammonium hydroxide are added while stirring pure water in the container, and the pH of the solution is controlled in an acidic range to form a siliceous gel. Manufacturing method.
[3] The above [1] or [2], wherein silicon tetrachloride is added while stirring pure water in the container and ammonium hydroxide is added in small portions to produce a siliceous gel at pH 1-2. A method for producing synthetic silica powder.
[4] The recovered gel is dried at 200 ° C. to 300 ° C., pulverized and classified to adjust the particle size, and further treated at a high temperature of 100 ° C. to 1500 ° C. to recover the synthetic silica powder. ] The manufacturing method of the synthetic silica powder in any one of.
本発明の製造方法は、加水分解で副生する塩酸に水酸化アンモニウムを添加して中和しながら反応を進行させるので酸性度が高くならず、ゲル化が遅くなるので、四塩化珪素の加水分解量を増加させることができ、すなわち、ゲル中のシリカ含有量が増加し、生産性が大幅に向上する。具体的には、例えば、水酸化アンモニアを添加せずに加水分解する場合に比べて、約２.０倍の四塩化珪素を加水分解することができる。 In the production method of the present invention, the reaction proceeds while neutralizing by adding ammonium hydroxide to hydrochloric acid by-produced by hydrolysis, so that the acidity does not increase and gelation is slowed down. The amount of decomposition can be increased, that is, the silica content in the gel is increased and the productivity is greatly improved. Specifically, for example, about 2.0 times as much silicon tetrachloride can be hydrolyzed as compared with the case of hydrolyzing without adding ammonia hydroxide.
さらに、本発明の製造方法は、四塩化珪素と共に水酸化アンモニウムを添加すればよく、煩雑な処理装置を必要としないので容易に実施することができる。 Furthermore, the production method of the present invention can be easily carried out because ammonium hydroxide is added together with silicon tetrachloride, and a complicated processing apparatus is not required.
以下、本発明を実施形態に基づいて具体的に説明する。なお％は原則として質量％である。 Hereinafter, the present invention will be specifically described based on embodiments. In addition,% is mass% in principle.
本発明の製造方法は、四塩化珪素の加水分解によってシリカ粉を製造する方法において、加水分解で副生する塩酸に水酸化アンモニウムを添加して中和しながら反応を進行させてシリカ質のゲルを生成させ、該ゲルを乾燥してシリカ粉にすることを特徴とする合成シリカ粉の製造方法である。 The production method of the present invention is a method for producing silica powder by hydrolyzing silicon tetrachloride. In the method for producing silica powder, silicic gel is prepared by adding ammonium hydroxide to hydrochloric acid by-produced by hydrolysis and allowing the reaction to proceed while neutralizing. Is produced, and the gel is dried to form a silica powder.
〔加水分解工程〕
容器内に純水を仕込み、この純水を攪拌しながら四塩化珪素と水酸化アンモニウムを添加する。上記式[１]に従って四塩化珪素が加水分解され、シリカ質のゲルが生成する。攪拌速度は１００〜３００rpm程度であればよく、強攪拌する必要はない。
[Hydrolysis step]
Pure water is charged into the container, and silicon tetrachloride and ammonium hydroxide are added while stirring the pure water. In accordance with the above formula [1], silicon tetrachloride is hydrolyzed to produce a siliceous gel. The stirring speed may be about 100 to 300 rpm and does not need to be vigorously stirred.
四塩化珪素は定量ポンプによって少量ずつ加えるのがよく、例えば、純水１０００ｇに対して四塩化珪素１〜５０ｇ/minの割合で添加すると良い。四塩化珪素の加水分解に伴って発熱するので、反応容器の外壁を冷却し、液温を５℃〜６０℃に調整する。 Silicon tetrachloride is preferably added little by little with a metering pump. For example, silicon tetrachloride is preferably added at a rate of 1 to 50 g / min of silicon tetrachloride with respect to 1000 g of pure water. Since heat is generated with the hydrolysis of silicon tetrachloride, the outer wall of the reaction vessel is cooled and the liquid temperature is adjusted to 5 ° C to 60 ° C.
本発明の製造方法は、溶液を所望のｐＨに調整するために、四塩化珪素と共に水酸化アンモニウムを少量ずつ添加する。水酸化アンモニウムを添加することによって、四塩化珪素の加水分解によって副生する塩酸が中和され、溶液の酸性度が高くならず、ゲル化が遅くなり、水酸化アンモニウムを添加しない場合よりも多量の四塩化珪素を加水分解することができる。 In the production method of the present invention, ammonium hydroxide is added little by little together with silicon tetrachloride in order to adjust the solution to a desired pH. By adding ammonium hydroxide, hydrochloric acid by-produced by hydrolysis of silicon tetrachloride is neutralized, the acidity of the solution is not increased, gelation is delayed, and a larger amount than when ammonium hydroxide is not added. The silicon tetrachloride can be hydrolyzed.
例えば、水酸化アンモニウムを添加せずに加水分解した場合には、概ね、純水１０００ｇに対して約１７０ｇの四塩化珪素が加水分解されるが、本発明の方法によれば、約３４０ｇの四塩化珪素を加水分解させることができる。 For example, when hydrolysis is performed without adding ammonium hydroxide, about 170 g of silicon tetrachloride is generally hydrolyzed with respect to 1000 g of pure water, but according to the method of the present invention, about 340 g of four tetrachlorides are hydrolyzed. Silicon chloride can be hydrolyzed.
水酸化アンモニウムの添加量は、四塩化珪素約１７０ｇに対して、水酸化アンモニウム約５０〜３００ｇが適当である。水酸化アンモニウムをこの量比の範囲で添加すれば、溶液の酸性度が高くならず、ｐＨを１〜７、好ましくはｐＨ１〜２の範囲に維持して加水分解を進行させることができる。 The amount of ammonium hydroxide added is appropriately about 50 to 300 g of ammonium hydroxide with respect to about 170 g of silicon tetrachloride. If ammonium hydroxide is added in the range of this quantitative ratio, the acidity of the solution does not increase, and the hydrolysis can proceed while maintaining the pH in the range of 1 to 7, preferably in the range of pH 1 to 2.
添加した水酸化アンモニウムは副生する塩酸と反応して塩化アンモニウム(ＮＨ4Ｃｌ)を生成するが、これは発熱反応に伴って蒸発させればよく、生成するシリカ粉への混入を防止することができる。 The added ammonium hydroxide reacts with the by-produced hydrochloric acid to produce ammonium chloride (NH 4 Cl), which should be evaporated in accordance with the exothermic reaction, and prevent mixing into the produced silica powder. Can do.
四塩化珪素の加水分解が進行すると溶液全体がゲル化して固化する。ゲル化した後は四塩化珪素を添加しても反応しないので、ゲル化した段階で四塩化珪素および水酸化アンモニウムの供給を停止する。 As the hydrolysis of silicon tetrachloride proceeds, the entire solution gels and solidifies. After the gelation, no reaction occurs even if silicon tetrachloride is added, so the supply of silicon tetrachloride and ammonium hydroxide is stopped at the stage of gelation.
〔乾燥工程〕
生成したゲルは多量の塩酸を含有するので、ゲルを２００℃〜３００℃で乾燥（低温乾燥）した後に、粉砕・分級し粒度分布を制御し、さらに１０００℃〜１５００℃で熱処理（高温処理）して非晶質の合成シリカ粉を回収する。
[Drying process]
Since the gel produced contains a large amount of hydrochloric acid, the gel is dried at 200 ° C to 300 ° C (low temperature drying), then pulverized and classified to control the particle size distribution, and further heat treated at 1000 ° C to 1500 ° C (high temperature treatment). Then, the amorphous synthetic silica powder is recovered.
上記低温乾燥は、例えば、フラスコに入れたゲルをマントルヒーターに入れて上記温度範囲に加熱し、上記高温処理は、低温乾燥したものを石英製の円筒形ボートに充填して加熱炉に入れ、上記の温度範囲に加熱して乾燥させるとよい。低温乾燥および高温処理の雰囲気は何れも大気下で行えばよい。 The low temperature drying, for example, put the gel placed in a flask in a mantle heater and heat to the above temperature range, the high temperature treatment is filled in a quartz cylindrical boat made of low temperature dried into a heating furnace, Heat to the above temperature range and dry. The atmosphere for the low temperature drying and the high temperature treatment may be performed in the air.
〔実施例１〕
攪拌機を装着したガラス製反応容器に１０００ｇの純水を注ぎ込み、攪拌しながら四塩化珪素液を定量ポンプで注入して加水分解させた。送液レートは２〜８ｇ/minの範囲で制御した。また、同様の送液手段を別系統で設け、溶液のｐＨが２に保持できるように、水酸化アンモニウム水溶液を反応容器に少量づつ供給した。
[Example 1]
1000 g of pure water was poured into a glass reaction vessel equipped with a stirrer, and hydrolyzed by injecting a silicon tetrachloride solution with a metering pump while stirring. The liquid feeding rate was controlled in the range of 2 to 8 g / min. Moreover, the same liquid feeding means was provided in another system, and an aqueous ammonium hydroxide solution was supplied to the reaction vessel little by little so that the pH of the solution could be maintained at 2.
四塩化珪素の加水分解に伴い発熱するため、反応容器外壁を循環冷却機を用いて冷却し、反応中の液温を４５〜６０℃の範囲に制御した。溶液全体がゲル化して固化した時点で反応終了とし、攪拌を止め四塩化珪素の供給を停止した。反応停止までに添加した四塩化珪素量は３４０ｇであった。 Since heat was generated with the hydrolysis of silicon tetrachloride, the outer wall of the reaction vessel was cooled using a circulating cooler, and the liquid temperature during the reaction was controlled in the range of 45 to 60 ° C. When the entire solution gelled and solidified, the reaction was terminated, stirring was stopped, and the supply of silicon tetrachloride was stopped. The amount of silicon tetrachloride added until the reaction was stopped was 340 g.
ゲルを容器から取り出し、約２００℃で低温乾燥した後に、１３５０°で高温処理を行った。低温乾燥はフラスコに入れたゲルをマントルヒーターに入れて加熱し、高温処理は石英製の円筒形ボートに充填した低温乾燥物を横型管状炉（外部抵抗加熱）に装入して加熱した。 The gel was taken out of the container, dried at a low temperature of about 200 ° C., and then subjected to a high temperature treatment at 1350 °. In the low temperature drying, the gel placed in the flask was put into a mantle heater and heated, and in the high temperature treatment, the low temperature dried material filled in a quartz cylindrical boat was charged in a horizontal tubular furnace (external resistance heating) and heated.
得られた合成シリカ粉を質量測定して収率を計算したところ、収率は約９％であった。収率は下記式[３]によって求めた。
収率＝合成シリカの質量／（純水の質量＋四塩化珪素の質量） …… [３]
When the obtained synthetic silica powder was weighed and the yield was calculated, the yield was about 9%. The yield was determined by the following formula [3].
Yield = mass of synthetic silica / (mass of pure water + mass of silicon tetrachloride) ...... [3]
〔実施例２、３〕
溶液のｐＨが表１に示す値になるように水酸化アンモニウムの添加速度を調整し、それ以外は実施例１と同様にして四塩化珪素の加水分解を行った。生成したゲルを実施例１と同様の乾燥および高温処理を行い、合成シリカ粉を回収した。この結果を表１に示した。
[Examples 2 and 3]
The addition rate of ammonium hydroxide was adjusted so that the pH of the solution was the value shown in Table 1, and silicon tetrachloride was hydrolyzed in the same manner as in Example 1 except that. The generated gel was dried and treated at a high temperature in the same manner as in Example 1 to recover synthetic silica powder. The results are shown in Table 1.
〔比較例〕
水酸化アンモニウムを添加せず、それ以外は実施例１と同様にして四塩化珪素の加水分解を行った。ゲル化するまでに添加した四塩化珪素の量は１７０ｇであった。生成したゲルを実施例１と同様の乾燥および高温処理を行い、合成シリカ粉を回収した。この合成シリカ粉の質量を測定し、上記式の[３]に基づき収率を計算したところ、収率は５.７％であった。
[Comparative example]
Silicon tetrachloride was hydrolyzed in the same manner as in Example 1 except that ammonium hydroxide was not added. The amount of silicon tetrachloride added before gelation was 170 g. The generated gel was dried and treated at a high temperature in the same manner as in Example 1 to recover synthetic silica powder. When the mass of this synthetic silica powder was measured and the yield was calculated based on [3] of the above formula, the yield was 5.7%.
Claims (4)
In the method for producing silica powder by hydrolysis of silicon tetrachloride, a reaction is allowed to proceed while neutralizing by adding ammonium hydroxide to hydrochloric acid by-produced by hydrolysis to produce a siliceous gel. A method for producing a synthetic silica powder, characterized by drying to form a silica powder.
The method for producing a synthetic silica powder according to claim 1, wherein silicon tetrachloride and ammonium hydroxide are added while stirring pure water in the container, and the pH of the solution is controlled in an acidic range to produce a siliceous gel.
The synthetic silica powder according to claim 1 or 2, wherein silicon tetrachloride is added while stirring pure water in the container, and ammonium hydroxide is added little by little to produce a siliceous gel at pH 1-2. Production method.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115180628A (en) * | 2022-06-27 | 2022-10-14 | 中琦(广东)硅材料股份有限公司 | Processing method of high-purity silicon dioxide powder |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115180628A (en) * | 2022-06-27 | 2022-10-14 | 中琦(广东)硅材料股份有限公司 | Processing method of high-purity silicon dioxide powder |
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